1. Field of the Invention
The present invention relates to an imaging device, an image forming apparatus, and a contamination inspection method.
2. Description of the Related Art
An imaging device is known that performs colorimetry for a pattern formed by an image forming apparatus on a recording medium using a coloring material such as ink, by capturing an image of the pattern using a two-dimensional image sensor and converting an RGB value of the pattern thus obtained into a color specification value in a standard color space (see, for example, Japanese Patent Application Laid-open No. 2013-207595).
The imaging device disclosed in Japanese Patent Application Laid-open No. 2013-207595 includes a transparent optical member (a mist blocking transparent member) to block an opening in a housing in which the two-dimensional image sensor is disposed, thereby preventing mist-like ink produced during the formation of the pattern from entering inside the housing. In order to detect contamination on the mist blocking transparent member, the imaging device disclosed in Japanese Patent Application Laid-open No. 2013-207595 captures two images with different distances between the recording medium and the housing and determines whether or not the mist blocking transparent member is contaminated on the basis of a difference in a contaminated pixel detected from the two images.
To inspect whether the mist blocking transparent member is contaminated, however, the imaging device disclosed in Japanese Patent Application Laid-open No. 2013-207595 is required to analyze the two images captured by changing the distance between the recording medium and the housing. A need thus exists for more convenient inspection of contamination on the optical member.